﻿using System;
using System.Windows;
using System.Windows.Controls;

namespace Monitorian.Core.Views.Controls;

[TemplatePart(Name = nameof(Named.PART_ShadowThumb), Type = typeof(FrameworkElement))]
[TemplatePart(Name = nameof(Named.PART_ShadowLeft), Type = typeof(ColumnDefinition))]
[TemplatePart(Name = nameof(Named.PART_ShadowRight), Type = typeof(ColumnDefinition))]
public class ShadowSlider : RangeSlider
{
	public override void OnApplyTemplate()
	{
		base.OnApplyTemplate();

		CheckCanUseShadow();
		ReflectShadow();
	}

	#region Shadow

	public bool IsShadowVisible
	{
		get { return (bool)GetValue(IsShadowVisibleProperty); }
		set { SetValue(IsShadowVisibleProperty, value); }
	}
	public static readonly DependencyProperty IsShadowVisibleProperty =
		DependencyProperty.Register(
			"IsShadowVisible",
			typeof(bool),
			typeof(ShadowSlider),
			new PropertyMetadata(
				false,
				(d, e) => ((ShadowSlider)d).ReflectShadow()));

	public double ValueShadow
	{
		get { return (double)GetValue(ValueShadowProperty); }
		set { SetValue(ValueShadowProperty, value); }
	}
	public static readonly DependencyProperty ValueShadowProperty =
		DependencyProperty.Register(
			"ValueShadow",
			typeof(double),
			typeof(ShadowSlider),
			new PropertyMetadata(
				-1D,
				(d, e) => ((ShadowSlider)d).ReflectShadow()));

	protected bool CanUseShadow { get; private set; }

	private void CheckCanUseShadow()
	{
		CanUseShadow = FindTemplateMembers();
	}

	private enum Named
	{
		PART_ShadowThumb,
		PART_ShadowLeft,
		PART_ShadowRight
	}

	private FrameworkElement _shadowThumb;
	private ColumnDefinition _shadowLeft;
	private ColumnDefinition _shadowRight;

	private bool FindTemplateMembers()
	{
		_shadowThumb = this.GetTemplateChild(nameof(Named.PART_ShadowThumb)) as FrameworkElement;
		_shadowLeft = this.GetTemplateChild(nameof(Named.PART_ShadowLeft)) as ColumnDefinition;
		_shadowRight = this.GetTemplateChild(nameof(Named.PART_ShadowRight)) as ColumnDefinition;

		return (_shadowThumb is not null)
			&& (_shadowLeft is not null)
			&& (_shadowRight is not null);
	}

	private void ReflectShadow()
	{
		if (!CanUseShadow)
			return;

		if (!IsShadowVisible || (ValueShadow < 0) || (ValueShadow == this.Value))
		{
			_shadowThumb.Visibility = Visibility.Collapsed;
			return;
		}
		else
		{
			_shadowThumb.Visibility = Visibility.Visible;
		}

		var ratio = Math.Min(ValueShadow / (this.Maximum - this.Minimum), 1D);

		_shadowLeft.Width = new GridLength(ratio, GridUnitType.Star);
		_shadowRight.Width = new GridLength(1D - ratio, GridUnitType.Star);
	}

	#endregion
}